Suspension arms, which are typically mounted on an upper hard point such as a ceiling, have been employed for some time to suspend equipment. Such suspension arms are used extensively in the medical area and also in other areas such as in hairdressers, whenever the suspension of fairly heavy equipment is needed.
A general feature of such suspension arms is that the equipment is generally removable and detachable from the arm, so a means of safe attachment to the arm is essential.
One common design involves a part of the suspension arm having a downwardly depending hollow housing, into which is inserted a corresponding element of the equipment to be suspended. The hollow housing and the insert both have an opening, which become aligned when fully inserted. A safety securing means is then inserted through the openings, which acts as a locking pin to prevent the subsequent removal of the insert from the housing.
Furthermore, to prevent the safety securing means from becoming dislodged from the openings in use, a sleeve is generally provided which covers the securing means, keeping it in place in the openings.
However, such sleeves necessarily can be moved into such a position that the safety securing means is exposed, as this is required to be able to insert the safety securing means in the first place.
Thus, steps have been taken to prevent the sleeve from moving into an unsafe position where the safety securing means could become dislodged.
One solution to the problem of the sleeve moving to an unsafe position is to add screws and the like to lock the sleeve in a safe position. In one solution, an internal nut is employed.
However, sometimes such devices need servicing, checked for compliance with safety requirements or for inspection following a collision. In such cases it is possible that such a suspension arm can be reassembled incorrectly, e.g. screws or nuts can be incorrectly placed, leading to the sleeve being capable of, or actually being in, an unsafe condition, exposing the safety securing means. When a screw or nut is not in place this can be difficult or impossible to see by visual inspection, leading to the error going uncorrected and increasing the risk of suspension failure.
In 2009 a large supplier of suspension arms issued a Field Safety Notice, which required that approximately 90,000 such suspension arms be checked for safety concerns. There has been at least one reported case of a supported device becoming detached following such a safety check.
Thus, improvements in preventing the unintended detachment of suspended devices is desirable.